ext4: fix use-after-free in ext4_orphan_cleanup
authorBaokun Li <libaokun1@huawei.com>
Wed, 2 Nov 2022 08:06:33 +0000 (16:06 +0800)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sat, 7 Jan 2023 10:11:58 +0000 (11:11 +0100)
commit7908b8a541b1578cc61b4da7f19b604a931441da
tree28a935feb7cbb7d7a2b196bcb133c5fb5bc48cdd
parenta73f2b2e385390b44d3503ab3464c25140b36b1b
ext4: fix use-after-free in ext4_orphan_cleanup

commit a71248b1accb2b42e4980afef4fa4a27fa0e36f5 upstream.

I caught a issue as follows:
==================================================================
 BUG: KASAN: use-after-free in __list_add_valid+0x28/0x1a0
 Read of size 8 at addr ffff88814b13f378 by task mount/710

 CPU: 1 PID: 710 Comm: mount Not tainted 6.1.0-rc3-next #370
 Call Trace:
  <TASK>
  dump_stack_lvl+0x73/0x9f
  print_report+0x25d/0x759
  kasan_report+0xc0/0x120
  __asan_load8+0x99/0x140
  __list_add_valid+0x28/0x1a0
  ext4_orphan_cleanup+0x564/0x9d0 [ext4]
  __ext4_fill_super+0x48e2/0x5300 [ext4]
  ext4_fill_super+0x19f/0x3a0 [ext4]
  get_tree_bdev+0x27b/0x450
  ext4_get_tree+0x19/0x30 [ext4]
  vfs_get_tree+0x49/0x150
  path_mount+0xaae/0x1350
  do_mount+0xe2/0x110
  __x64_sys_mount+0xf0/0x190
  do_syscall_64+0x35/0x80
  entry_SYSCALL_64_after_hwframe+0x63/0xcd
  </TASK>
 [...]
==================================================================

Above issue may happen as follows:
-------------------------------------
ext4_fill_super
  ext4_orphan_cleanup
   --- loop1: assume last_orphan is 12 ---
    list_add(&EXT4_I(inode)->i_orphan, &EXT4_SB(sb)->s_orphan)
    ext4_truncate --> return 0
      ext4_inode_attach_jinode --> return -ENOMEM
    iput(inode) --> free inode<12>
   --- loop2: last_orphan is still 12 ---
    list_add(&EXT4_I(inode)->i_orphan, &EXT4_SB(sb)->s_orphan);
    // use inode<12> and trigger UAF

To solve this issue, we need to propagate the return value of
ext4_inode_attach_jinode() appropriately.

Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20221102080633.1630225-1-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
fs/ext4/inode.c